electrolysis

"Electrolysis

The decomposition of an ionic compound using electricity"

what should Ionic compounds in electrolysis be

Must be molten or dissolved so ions can move"

Why ionic compounds must be molten

so ions are free to carry charge"

"Electrodes

Conducting rods that pass electricity into electrolyte"

"Cathode

Negative electrode where reduction occurs"

"Anode

Positive electrode where oxidation occurs"

"Oxidation

Loss of electrons"

"Reduction

Gain of electrons"

"Electrolyte

Liquid containing free ions that conducts electricity"

what is the Movement of positive ions

They move to the cathode and gain electrons"

"Movement of negative ions

They move to the anode and lose electrons"

"Ionic half equation

Equation showing electron transfer"

what is Aluminium ore

Bauxite"

"Purified bauxite

Aluminium oxide Al2O3"

"Role of cryolite

Lowers melting point of aluminium oxide to save energy"

"Electrolyte in extraction of aluminium

Molten aluminium oxide dissolved in cryolite"

"Cathode product in aluminium extraction

Aluminium metal"

"Cathode half equation for aluminium

Al3+ + 3e- → Al"

"Anode product in aluminium extraction

Oxygen gas"

"Anode half equation for oxygen

2O2- → O2 + 4e-"

"Why carbon anodes replaced

React with oxygen to form carbon dioxide"

"Why aluminium extraction expensive

Uses large amounts of electricity and high temperatures"

"Aqueous ions present

H+ and OH- ions from water"

"Cathode rule for aqueous solutions

Least reactive positive ion is discharged"

"Hydrogen at cathode

If metal is more reactive than hydrogen H2 forms"

"Cathode half equation for hydrogen

2H+ + 2e- → H2"

"Less reactive metal at cathode

If metal less reactive than hydrogen it is deposited"

"Anode rule for aqueous

Usually oxygen unless halide ions present"

"Anode half equation for oxygen

4OH- → O2 + 2H2O + 4e-"

"Halide ions at anode

Chlorine bromine or iodine gas produced"

"Test for hydrogen

Squeaky pop with lit splint"

"Test for oxygen

Relights a glowing splint"